21764379 has 32 divisors (see below), whose sum is σ = 36467200. Its totient is φ = 11473056.

The previous prime is 21764341. The next prime is 21764381. The reversal of 21764379 is 97346712.

It is not a de Polignac number, because 21764379 - 2²¹ = 19667227 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is not an unprimeable number, because it can be changed into a prime (21764179) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 12564 + ... + 14190.

It is an arithmetic number, because the mean of its divisors is an integer number (1139600).

Almost surely, 2^21764379 is an apocalyptic number.

21764379 is a deficient number, since it is larger than the sum of its proper divisors (14702821).

21764379 is a wasteful number, since it uses less digits than its factorization.

21764379 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1664 (or 1650 counting only the distinct ones).

The product of its digits is 63504, while the sum is 39.

The square root of 21764379 is about 4665.2308624547. The cubic root of 21764379 is about 279.2000081759.

It can be divided in two parts, 2176 and 4379, that added together give a triangular number (6555 = T₁₁₄).

The spelling of 21764379 in words is "twenty-one million, seven hundred sixty-four thousand, three hundred seventy-nine".