15681920 has 64 divisors (see below), whose sum is σ = 38005200. Its totient is φ = 6187008.

The previous prime is 15681899. The next prime is 15681923. The reversal of 15681920 is 2918651.

It is a tau number, because it is divible by the number of its divisors (64).

It is a super-2 number, since 2×15681920² = 491845229772800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15681923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 68366 + ... + 68594.

Almost surely, 2^15681920 is an apocalyptic number.

15681920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 15681920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (19002600).

15681920 is an abundant number, since it is smaller than the sum of its proper divisors (22323280).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

15681920 is a wasteful number, since it uses less digits than its factorization.

15681920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 355 (or 343 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 32.

The square root of 15681920 is about 3960.0404038343. The cubic root of 15681920 is about 250.3032054505.

The spelling of 15681920 in words is "fifteen million, six hundred eighty-one thousand, nine hundred twenty".