21031497 has 12 divisors (see below), whose sum is σ = 30494464. Its totient is φ = 13967640.

The previous prime is 21031487. The next prime is 21031529. The reversal of 21031497 is 79413012.

It is not a de Polignac number, because 21031497 - 2⁴ = 21031481 is a prime.

It is a super-2 number, since 2×21031497² = 884647732122018, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21031497.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21031457) 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, 1873 + ... + 6750.

Almost surely, 2^21031497 is an apocalyptic number.

It is an amenable number.

21031497 is a deficient number, since it is larger than the sum of its proper divisors (9462967).

21031497 is a wasteful number, since it uses less digits than its factorization.

21031497 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8900 (or 8897 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 27.

The square root of 21031497 is about 4586.0110117617. The cubic root of 21031497 is about 276.0302818066.

It can be divided in two parts, 21031 and 497, that added together give a triangular number (21528 = T₂₀₇).

The spelling of 21031497 in words is "twenty-one million, thirty-one thousand, four hundred ninety-seven".