1021377681 has 45 divisors (see below), whose sum is σ = 1578649611. Its totient is φ = 658099728.

The previous prime is 1021377673. The next prime is 1021377689. The reversal of 1021377681 is 1867731201.

The square root of 1021377681 is 31959.

It is a perfect power (a square), and thus also a powerful number.

It is an interprime number because it is at equal distance from previous prime (1021377673) and next prime (1021377689).

It can be written as a sum of positive squares in only one way, i.e., 736308225 + 285069456 = 27135^2 + 16884^2 .

It is not a de Polignac number, because 1021377681 - 2³ = 1021377673 is a prime.

It is a super-2 number, since 2×1021377681² = 2086424734489875522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1021377689) by changing a digit.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 15244410 + ... + 15244476.

Almost surely, 2^1021377681 is an apocalyptic number.

1021377681 is the 31959-th square number.

1021377681 is the 15980-th centered octagonal number.

It is an amenable number.

1021377681 is a deficient number, since it is larger than the sum of its proper divisors (557271930).

1021377681 is an frugal number, since it uses more digits than its factorization.

1021377681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 252 (or 123 counting only the distinct ones).

The product of its (nonzero) digits is 14112, while the sum is 36.

The cubic root of 1021377681 is about 1007.0757099125.

Multiplying 1021377681 by its sum of digits (36), we get a square (36769596516 = 191754²).

The spelling of 1021377681 in words is "one billion, twenty-one million, three hundred seventy-seven thousand, six hundred eighty-one".