21492945 has 20 divisors (see below), whose sum is σ = 38528820. Its totient is φ = 11462688.

The previous prime is 21492941. The next prime is 21492949. The reversal of 21492945 is 54929412.

It is an interprime number because it is at equal distance from previous prime (21492941) and next prime (21492949).

It can be written as a sum of positive squares in 2 ways, for example, as 16184529 + 5308416 = 4023^2 + 2304^2 .

It is not a de Polignac number, because 21492945 - 2² = 21492941 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is not an unprimeable number, because it can be changed into a prime (21492941) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 26130 + ... + 26939.

It is an arithmetic number, because the mean of its divisors is an integer number (1926441).

Almost surely, 2^21492945 is an apocalyptic number.

It is an amenable number.

21492945 is a deficient number, since it is larger than the sum of its proper divisors (17035875).

21492945 is an equidigital number, since it uses as much as digits as its factorization.

21492945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53086 (or 53077 counting only the distinct ones).

The product of its digits is 25920, while the sum is 36.

The square root of 21492945 is about 4636.0484251138. The cubic root of 21492945 is about 278.0344703043.

The spelling of 21492945 in words is "twenty-one million, four hundred ninety-two thousand, nine hundred forty-five".