21312742 has 8 divisors (see below), whose sum is σ = 34875432. Its totient is φ = 9687600.

The previous prime is 21312727. The next prime is 21312751. The reversal of 21312742 is 24721312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a Harshad number since it is a multiple of its sum of digits (22), and also a Moran number because the ratio is a prime number: 968761 = 21312742 / (2 + 1 + 3 + 1 + 2 + 7 + 4 + 2).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 484359 + ... + 484402.

It is an arithmetic number, because the mean of its divisors is an integer number (4359429).

Almost surely, 2^21312742 is an apocalyptic number.

21312742 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21312742 is a deficient number, since it is larger than the sum of its proper divisors (13562690).

21312742 is a wasteful number, since it uses less digits than its factorization.

21312742 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 968774.

The product of its digits is 672, while the sum is 22.

The square root of 21312742 is about 4616.5725381499. The cubic root of 21312742 is about 277.2552483082.

The spelling of 21312742 in words is "twenty-one million, three hundred twelve thousand, seven hundred forty-two".