21949407 has 16 divisors (see below), whose sum is σ = 32590080. Its totient is φ = 14600376.

The previous prime is 21949387. The next prime is 21949409. The reversal of 21949407 is 70494912.

21949407 is nontrivially palindromic in base 5.

It is not a de Polignac number, because 21949407 - 2¹⁶ = 21883871 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21949409) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21838 + ... + 22820.

It is an arithmetic number, because the mean of its divisors is an integer number (2036880).

Almost surely, 2^21949407 is an apocalyptic number.

21949407 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

21949407 is a deficient number, since it is larger than the sum of its proper divisors (10640673).

21949407 is an equidigital number, since it uses as much as digits as its factorization.

21949407 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1819 (or 1813 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The square root of 21949407 is about 4685.0194236524. The cubic root of 21949407 is about 279.9889749060.

The spelling of 21949407 in words is "twenty-one million, nine hundred forty-nine thousand, four hundred seven".