21790551 has 16 divisors (see below), whose sum is σ = 30694400. Its totient is φ = 13728960.

The previous prime is 21790541. The next prime is 21790567. The reversal of 21790551 is 15509712.

It is not a de Polignac number, because 21790551 - 2⁵ = 21790519 is a prime.

It is a super-2 number, since 2×21790551² = 949656225767202, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21790541) 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, 1275 + ... + 6723.

It is an arithmetic number, because the mean of its divisors is an integer number (1918400).

Almost surely, 2^21790551 is an apocalyptic number.

21790551 is a deficient number, since it is larger than the sum of its proper divisors (8903849).

21790551 is a wasteful number, since it uses less digits than its factorization.

21790551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5526.

The product of its (nonzero) digits is 3150, while the sum is 30.

The square root of 21790551 is about 4668.0350255755. The cubic root of 21790551 is about 279.3118774456.

The spelling of 21790551 in words is "twenty-one million, seven hundred ninety thousand, five hundred fifty-one".