21981052 has 6 divisors (see below), whose sum is σ = 38466848. Its totient is φ = 10990524.

The previous prime is 21981013. The next prime is 21981053. The reversal of 21981052 is 25018912.

It is a self number, because there is not a number n which added to its sum of digits gives 21981052.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21981053) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2747628 + ... + 2747635.

Almost surely, 2^21981052 is an apocalyptic number.

It is an amenable number.

21981052 is a deficient number, since it is larger than the sum of its proper divisors (16485796).

21981052 is a wasteful number, since it uses less digits than its factorization.

21981052 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5495267 (or 5495265 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 28.

The square root of 21981052 is about 4688.3954611359. The cubic root of 21981052 is about 280.1234659579.

Adding to 21981052 its reverse (25018912), we get a palindrome (46999964).

The spelling of 21981052 in words is "twenty-one million, nine hundred eighty-one thousand, fifty-two".