21492437 has 4 divisors (see below), whose sum is σ = 22756716. Its totient is φ = 20228160.

The previous prime is 21492433. The next prime is 21492463. The reversal of 21492437 is 73429412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 19061956 + 2430481 = 4366^2 + 1559^2 .

It is a cyclic number.

It is not a de Polignac number, because 21492437 - 2² = 21492433 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21492433) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 632114 + ... + 632147.

It is an arithmetic number, because the mean of its divisors is an integer number (5689179).

Almost surely, 2^21492437 is an apocalyptic number.

It is an amenable number.

21492437 is a deficient number, since it is larger than the sum of its proper divisors (1264279).

21492437 is a wasteful number, since it uses less digits than its factorization.

21492437 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1264278.

The product of its digits is 12096, while the sum is 32.

The square root of 21492437 is about 4635.9936367515. The cubic root of 21492437 is about 278.0322797774.

The spelling of 21492437 in words is "twenty-one million, four hundred ninety-two thousand, four hundred thirty-seven".