21621742 has 8 divisors (see below), whose sum is σ = 32457600. Its totient is φ = 10802544.

The previous prime is 21621737. The next prime is 21621757. The reversal of 21621742 is 24712612.

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

It is a super-2 number, since 2×21621742² = 934999454229128, which contains 22 as substring.

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, 142 + ... + 6577.

It is an arithmetic number, because the mean of its divisors is an integer number (4057200).

Almost surely, 2^21621742 is an apocalyptic number.

21621742 is a deficient number, since it is larger than the sum of its proper divisors (10835858).

21621742 is a wasteful number, since it uses less digits than its factorization.

21621742 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8330.

The product of its digits is 1344, while the sum is 25.

The square root of 21621742 is about 4649.9184939093. The cubic root of 21621742 is about 278.5887407418.

The spelling of 21621742 in words is "twenty-one million, six hundred twenty-one thousand, seven hundred forty-two".