21451770 has 32 divisors (see below), whose sum is σ = 57205440. Its totient is φ = 5720400.

The previous prime is 21451769. The next prime is 21451789. The reversal of 21451770 is 7715412.

It is a super-2 number, since 2×21451770² = 920356872265800, which contains 22 as substring.

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

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 39456 + ... + 39995.

It is an arithmetic number, because the mean of its divisors is an integer number (1787670).

Almost surely, 2^21451770 is an apocalyptic number.

21451770 is an abundant number, since it is smaller than the sum of its proper divisors (35753670).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21451770 is a wasteful number, since it uses less digits than its factorization.

21451770 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79467 (or 79461 counting only the distinct ones).

The product of its (nonzero) digits is 1960, while the sum is 27.

The square root of 21451770 is about 4631.6055531532. The cubic root of 21451770 is about 277.8568090976.

It can be divided in two parts, 214 and 51770, that added together give a square (51984 = 228²).

The spelling of 21451770 in words is "twenty-one million, four hundred fifty-one thousand, seven hundred seventy".