21701388 has 36 divisors (see below), whose sum is σ = 52081512. Its totient is φ = 7032960.

The previous prime is 21701377. The next prime is 21701389. The reversal of 21701388 is 88310712.

It is a happy number.

It is a super-2 number, since 2×21701388² = 941900482253088, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21701389) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 15768 + ... + 17088.

Almost surely, 2^21701388 is an apocalyptic number.

It is an amenable number.

21701388 is an abundant number, since it is smaller than the sum of its proper divisors (30380124).

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

21701388 is a wasteful number, since it uses less digits than its factorization.

21701388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1402 (or 1363 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 30.

The square root of 21701388 is about 4658.4748577190. The cubic root of 21701388 is about 278.9303920592.

The spelling of 21701388 in words is "twenty-one million, seven hundred one thousand, three hundred eighty-eight".