21957145 has 40 divisors (see below), whose sum is σ = 32267520. Its totient is φ = 14323680.

The previous prime is 21957139. The next prime is 21957151. The reversal of 21957145 is 54175912.

It is an interprime number because it is at equal distance from previous prime (21957139) and next prime (21957151).

It is not a de Polignac number, because 21957145 - 2¹⁷ = 21826073 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21957145.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 372126 + ... + 372184.

It is an arithmetic number, because the mean of its divisors is an integer number (806688).

Almost surely, 2^21957145 is an apocalyptic number.

It is an amenable number.

21957145 is a deficient number, since it is larger than the sum of its proper divisors (10310375).

21957145 is an frugal number, since it uses more digits than its factorization.

21957145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123 (or 102 counting only the distinct ones).

The product of its digits is 12600, while the sum is 34.

The square root of 21957145 is about 4685.8451745656. The cubic root of 21957145 is about 280.0218732912.

The spelling of 21957145 in words is "twenty-one million, nine hundred fifty-seven thousand, one hundred forty-five".