21397190 has 16 divisors (see below), whose sum is σ = 38631600. Its totient is φ = 8532960.

The previous prime is 21397171. The next prime is 21397217. The reversal of 21397190 is 9179312.

It is a happy number.

It is a super-2 number, since 2×21397190² = 915679479792200, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 425 + ... + 6555.

It is an arithmetic number, because the mean of its divisors is an integer number (2414475).

Almost surely, 2^21397190 is an apocalyptic number.

21397190 is a deficient number, since it is larger than the sum of its proper divisors (17234410).

21397190 is a wasteful number, since it uses less digits than its factorization.

21397190 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6487.

The product of its (nonzero) digits is 3402, while the sum is 32.

The square root of 21397190 is about 4625.7096752823. The cubic root of 21397190 is about 277.6209574685.

The spelling of 21397190 in words is "twenty-one million, three hundred ninety-seven thousand, one hundred ninety".