21960621 has 6 divisors (see below), whose sum is σ = 31720910. Its totient is φ = 14640408.

The previous prime is 21960619. The next prime is 21960641. The reversal of 21960621 is 12606912.

It can be written as a sum of positive squares in only one way, i.e., 21958596 + 2025 = 4686^2 + 45^2 .

It is not a de Polignac number, because 21960621 - 2¹ = 21960619 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21960611) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1220026 + ... + 1220043.

Almost surely, 2^21960621 is an apocalyptic number.

It is an amenable number.

21960621 is a deficient number, since it is larger than the sum of its proper divisors (9760289).

21960621 is a wasteful number, since it uses less digits than its factorization.

21960621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2440075 (or 2440072 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The square root of 21960621 is about 4686.2160641609. The cubic root of 21960621 is about 280.0366491144.

The spelling of 21960621 in words is "twenty-one million, nine hundred sixty thousand, six hundred twenty-one".