21492457 has 4 divisors (see below), whose sum is σ = 24562816. Its totient is φ = 18422100.

The previous prime is 21492433. The next prime is 21492463. The reversal of 21492457 is 75429412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21492457 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21492157) 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, 1535169 + ... + 1535182.

It is an arithmetic number, because the mean of its divisors is an integer number (6140704).

Almost surely, 2^21492457 is an apocalyptic number.

It is an amenable number.

21492457 is a deficient number, since it is larger than the sum of its proper divisors (3070359).

21492457 is an equidigital number, since it uses as much as digits as its factorization.

21492457 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3070358.

The product of its digits is 20160, while the sum is 34.

The square root of 21492457 is about 4635.9957937858. The cubic root of 21492457 is about 278.0323660193.

The spelling of 21492457 in words is "twenty-one million, four hundred ninety-two thousand, four hundred fifty-seven".