21977001 has 20 divisors (see below), whose sum is σ = 33721732. Its totient is φ = 14253408.

The previous prime is 21976979. The next prime is 21977023. The reversal of 21977001 is 10077912.

It is an interprime number because it is at equal distance from previous prime (21976979) and next prime (21977023).

It can be written as a sum of positive squares in 2 ways, for example, as 8294400 + 13682601 = 2880^2 + 3699^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21977001 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21977101) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 670 + ... + 6663.

Almost surely, 2^21977001 is an apocalyptic number.

It is an amenable number.

21977001 is a deficient number, since it is larger than the sum of its proper divisors (11744731).

21977001 is an equidigital number, since it uses as much as digits as its factorization.

21977001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7382 (or 7373 counting only the distinct ones).

The product of its (nonzero) digits is 882, while the sum is 27.

The square root of 21977001 is about 4687.9634170928. The cubic root of 21977001 is about 280.1062564406.

The spelling of 21977001 in words is "twenty-one million, nine hundred seventy-seven thousand, one".