261520947 has 16 divisors (see below), whose sum is σ = 391063680. Its totient is φ = 172715976.

The previous prime is 261520939. The next prime is 261520951. The reversal of 261520947 is 749025162.

It is not a de Polignac number, because 261520947 - 2³ = 261520939 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (261520957) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 42373 + ... + 48150.

It is an arithmetic number, because the mean of its divisors is an integer number (24441480).

Almost surely, 2^261520947 is an apocalyptic number.

261520947 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

261520947 is a deficient number, since it is larger than the sum of its proper divisors (129542733).

261520947 is a wasteful number, since it uses less digits than its factorization.

261520947 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90639 (or 90633 counting only the distinct ones).

The product of its (nonzero) digits is 30240, while the sum is 36.

The square root of 261520947 is about 16171.6092891215. The cubic root of 261520947 is about 639.4925559340.

The spelling of 261520947 in words is "two hundred sixty-one million, five hundred twenty thousand, nine hundred forty-seven".