209561972 has 6 divisors (see below), whose sum is σ = 366733458. Its totient is φ = 104780984.

The previous prime is 209561929. The next prime is 209561987. The reversal of 209561972 is 279165902.

It can be written as a sum of positive squares in only one way, i.e., 209554576 + 7396 = 14476^2 + 86^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 26195243 + ... + 26195250.

It is an arithmetic number, because the mean of its divisors is an integer number (61122243).

Almost surely, 2^209561972 is an apocalyptic number.

It is an amenable number.

209561972 is a deficient number, since it is larger than the sum of its proper divisors (157171486).

209561972 is a wasteful number, since it uses less digits than its factorization.

209561972 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52390497 (or 52390495 counting only the distinct ones).

The product of its (nonzero) digits is 68040, while the sum is 41.

The square root of 209561972 is about 14476.2554550547. The cubic root of 209561972 is about 593.9786370880.

The spelling of 209561972 in words is "two hundred nine million, five hundred sixty-one thousand, nine hundred seventy-two".