21497442 has 16 divisors (see below), whose sum is σ = 43042752. Its totient is φ = 7157840.

The previous prime is 21497429. The next prime is 21497467. The reversal of 21497442 is 24479412.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax 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, 6892 + ... + 9512.

It is an arithmetic number, because the mean of its divisors is an integer number (2690172).

Almost surely, 2^21497442 is an apocalyptic number.

21497442 is an abundant number, since it is smaller than the sum of its proper divisors (21545310).

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

21497442 is a wasteful number, since it uses less digits than its factorization.

21497442 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3993.

The product of its digits is 16128, while the sum is 33.

The square root of 21497442 is about 4636.5334033090. The cubic root of 21497442 is about 278.0538601370.

It can be divided in two parts, 2149 and 7442, that added together give a triangular number (9591 = T₁₃₈).

The spelling of 21497442 in words is "twenty-one million, four hundred ninety-seven thousand, four hundred forty-two".