1631751561 has 24 divisors (see below), whose sum is σ = 2666480544. Its totient is φ = 988938720.

The previous prime is 1631751551. The next prime is 1631751601. The reversal of 1631751561 is 1651571361.

1631751561 is a `hidden beast` number, since 1 + 631 + 7 + 5 + 15 + 6 + 1 = 666.

It is not a de Polignac number, because 1631751561 - 2¹⁰ = 1631750537 is a prime.

It is a super-2 number, since 2×1631751561² = 5325226313651873442, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1631751551) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 302556 + ... + 307901.

It is an arithmetic number, because the mean of its divisors is an integer number (111103356).

Almost surely, 2^1631751561 is an apocalyptic number.

1631751561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1631751561 is a deficient number, since it is larger than the sum of its proper divisors (1034728983).

1631751561 is an equidigital number, since it uses as much as digits as its factorization.

1631751561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 610483 (or 610471 counting only the distinct ones).

The product of its digits is 18900, while the sum is 36.

The square root of 1631751561 is about 40394.9447455990. The cubic root of 1631751561 is about 1177.2933176125.

The spelling of 1631751561 in words is "one billion, six hundred thirty-one million, seven hundred fifty-one thousand, five hundred sixty-one".