21077931 has 8 divisors (see below), whose sum is σ = 32118784. Its totient is φ = 12044520.

The previous prime is 21077929. The next prime is 21077951. The reversal of 21077931 is 13977012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21077931 - 2¹ = 21077929 is a prime.

It is a super-2 number, since 2×21077931² = 888558350481522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21077951) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 501835 + ... + 501876.

It is an arithmetic number, because the mean of its divisors is an integer number (4014848).

Almost surely, 2^21077931 is an apocalyptic number.

21077931 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21077931 is a deficient number, since it is larger than the sum of its proper divisors (11040853).

21077931 is a wasteful number, since it uses less digits than its factorization.

21077931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1003721.

The product of its (nonzero) digits is 2646, while the sum is 30.

The square root of 21077931 is about 4591.0707901316. The cubic root of 21077931 is about 276.2332752649.

The spelling of 21077931 in words is "twenty-one million, seventy-seven thousand, nine hundred thirty-one".