21237494 has 4 divisors (see below), whose sum is σ = 31856244. Its totient is φ = 10618746.

The previous prime is 21237493. The next prime is 21237509. The reversal of 21237494 is 49473212.

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

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21237494.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21237493) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5309372 + ... + 5309375.

It is an arithmetic number, because the mean of its divisors is an integer number (7964061).

Almost surely, 2^21237494 is an apocalyptic number.

21237494 is a deficient number, since it is larger than the sum of its proper divisors (10618750).

21237494 is a wasteful number, since it uses less digits than its factorization.

21237494 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10618749.

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

The square root of 21237494 is about 4608.4155628589. The cubic root of 21237494 is about 276.9285657309.

The spelling of 21237494 in words is "twenty-one million, two hundred thirty-seven thousand, four hundred ninety-four".