21270621 has 16 divisors (see below), whose sum is σ = 30542400. Its totient is φ = 13118208.

The previous prime is 21270593. The next prime is 21270629. The reversal of 21270621 is 12607212.

It is not a de Polignac number, because 21270621 - 2⁵ = 21270589 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21270629) 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, 526 + ... + 6543.

It is an arithmetic number, because the mean of its divisors is an integer number (1908900).

Almost surely, 2^21270621 is an apocalyptic number.

It is an amenable number.

21270621 is a deficient number, since it is larger than the sum of its proper divisors (9271779).

21270621 is a wasteful number, since it uses less digits than its factorization.

21270621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7148.

The product of its (nonzero) digits is 336, while the sum is 21.

The square root of 21270621 is about 4612.0083477808. The cubic root of 21270621 is about 277.0724786120.

Adding to 21270621 its reverse (12607212), we get a palindrome (33877833).

The spelling of 21270621 in words is "twenty-one million, two hundred seventy thousand, six hundred twenty-one".