1651131981 has 12 divisors (see below), whose sum is σ = 2488663008. Its totient is φ = 1052895624.

The previous prime is 1651131971. The next prime is 1651132001. The reversal of 1651131981 is 1891311561.

It is not a de Polignac number, because 1651131981 - 2¹⁸ = 1650869837 is a prime.

It is a super-2 number, since 2×1651131981² = 5452473637361968722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1651131971) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3988035 + ... + 3988448.

It is an arithmetic number, because the mean of its divisors is an integer number (207388584).

Almost surely, 2^1651131981 is an apocalyptic number.

It is an amenable number.

1651131981 is a deficient number, since it is larger than the sum of its proper divisors (837531027).

1651131981 is a wasteful number, since it uses less digits than its factorization.

1651131981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7976512 (or 7976509 counting only the distinct ones).

The product of its digits is 6480, while the sum is 36.

The square root of 1651131981 is about 40634.1233570998. The cubic root of 1651131981 is about 1181.9359155994.

The spelling of 1651131981 in words is "one billion, six hundred fifty-one million, one hundred thirty-one thousand, nine hundred eighty-one".