21790739 has 4 divisors (see below), whose sum is σ = 22937640. Its totient is φ = 20643840.

The previous prime is 21790711. The next prime is 21790801. The reversal of 21790739 is 93709712.

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

It is a cyclic number.

It is not a de Polignac number, because 21790739 - 2¹² = 21786643 is a prime.

It is a super-2 number, since 2×21790739² = 949672612332242, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21796739) 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, 573422 + ... + 573459.

It is an arithmetic number, because the mean of its divisors is an integer number (5734410).

Almost surely, 2^21790739 is an apocalyptic number.

21790739 is a deficient number, since it is larger than the sum of its proper divisors (1146901).

21790739 is a wasteful number, since it uses less digits than its factorization.

21790739 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1146900.

The product of its (nonzero) digits is 23814, while the sum is 38.

The square root of 21790739 is about 4668.0551624847. The cubic root of 21790739 is about 279.3126807063.

The spelling of 21790739 in words is "twenty-one million, seven hundred ninety thousand, seven hundred thirty-nine".