21940477 has 4 divisors (see below), whose sum is σ = 23628220. Its totient is φ = 20252736.

The previous prime is 21940441. The next prime is 21940483. The reversal of 21940477 is 77404912.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4726276 + 17214201 = 2174^2 + 4149^2 .

It is a cyclic number.

It is not a de Polignac number, because 21940477 - 2²³ = 13551869 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21940427) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 843852 + ... + 843877.

It is an arithmetic number, because the mean of its divisors is an integer number (5907055).

Almost surely, 2^21940477 is an apocalyptic number.

It is an amenable number.

21940477 is a deficient number, since it is larger than the sum of its proper divisors (1687743).

21940477 is a wasteful number, since it uses less digits than its factorization.

21940477 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1687742.

The product of its (nonzero) digits is 14112, while the sum is 34.

The square root of 21940477 is about 4684.0662890271. The cubic root of 21940477 is about 279.9509990782.

The spelling of 21940477 in words is "twenty-one million, nine hundred forty thousand, four hundred seventy-seven".