21947425 has 24 divisors (see below), whose sum is σ = 29134296. Its totient is φ = 16343040.

The previous prime is 21947417. The next prime is 21947447. The reversal of 21947425 is 52474912.

It can be written as a sum of positive squares in 12 ways, for example, as 5202961 + 16744464 = 2281^2 + 4092^2 .

It is not a de Polignac number, because 21947425 - 2³ = 21947417 is a prime.

It is a hoax number, since the sum of its digits (34) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

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 23 ways as a sum of consecutive naturals, for example, 47797 + ... + 48253.

It is an arithmetic number, because the mean of its divisors is an integer number (1213929).

Almost surely, 2^21947425 is an apocalyptic number.

21947425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21947425 is a deficient number, since it is larger than the sum of its proper divisors (7186871).

21947425 is a wasteful number, since it uses less digits than its factorization.

21947425 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 597 (or 592 counting only the distinct ones).

The product of its digits is 20160, while the sum is 34.

The square root of 21947425 is about 4684.8078936067. The cubic root of 21947425 is about 279.9805471179.

The spelling of 21947425 in words is "twenty-one million, nine hundred forty-seven thousand, four hundred twenty-five".