21612493 has 16 divisors (see below), whose sum is σ = 25280640. Its totient is φ = 18095616.

The previous prime is 21612431. The next prime is 21612497. The reversal of 21612493 is 39421612.

It is not a de Polignac number, because 21612493 - 2¹³ = 21604301 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21612497) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 70246 + ... + 70552.

It is an arithmetic number, because the mean of its divisors is an integer number (1580040).

Almost surely, 2^21612493 is an apocalyptic number.

It is an amenable number.

21612493 is a deficient number, since it is larger than the sum of its proper divisors (3668147).

21612493 is a wasteful number, since it uses less digits than its factorization.

21612493 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 516.

The product of its digits is 2592, while the sum is 28.

The square root of 21612493 is about 4648.9238539688. The cubic root of 21612493 is about 278.5490116772.

The spelling of 21612493 in words is "twenty-one million, six hundred twelve thousand, four hundred ninety-three".