21993402 has 16 divisors (see below), whose sum is σ = 44033472. Its totient is φ = 7323360.

The previous prime is 21993401. The next prime is 21993409. The reversal of 21993402 is 20439912.

It is a self number, because there is not a number n which added to its sum of digits gives 21993402.

It is not an unprimeable number, because it can be changed into a prime (21993401) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8502 + ... + 10782.

It is an arithmetic number, because the mean of its divisors is an integer number (2752092).

Almost surely, 2^21993402 is an apocalyptic number.

21993402 is an abundant number, since it is smaller than the sum of its proper divisors (22040070).

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

21993402 is a wasteful number, since it uses less digits than its factorization.

21993402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3893.

The product of its (nonzero) digits is 3888, while the sum is 30.

The square root of 21993402 is about 4689.7123579171. The cubic root of 21993402 is about 280.1759183625.

The spelling of 21993402 in words is "twenty-one million, nine hundred ninety-three thousand, four hundred two".